Method and apparatus for providing service in wireless communication system

ABSTRACT

The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. 
     Methods and apparatuses provide a service to user equipment through a dedicated core network. In one method, a base station, also referred to as eNB, receives a non-access stratum (NAS) message from user equipment (UE), and transmits a first initial UE message having the NAS message to a first mobility management entity (MME). Also, the base station receives a redirection request message having the NAS message from the first MME, and transmits a second initial UE message having the NAS message to a second MME. In another method, the MME receives the first initial UE message having the NAS message from the base station, and transmits the redirection request message having the NAS message when the MME fails to support a dedicated core network according to UE usage type information. If the redirection request message is transmitted, a second initial UE message having the NAS message is transmitted to a dedicated MME.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional application Nos. 62/126,917 filed on Mar. 2, 2015,62/202,406 filed on Aug. 7, 2015 and 62/232,100 filed on Sep. 24, 2015in the U.S. patent and trademark office, the entire disclosure of whichis hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a wireless communication system and,more particularly, to a method and apparatus for providing a service touser equipment through a dedicated core network.

BACKGROUND

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a ‘Beyond 4G Network’ or a‘Post LTE System’. The 5G communication system is considered to beimplemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, soas to accomplish higher data rates. To decrease propagation loss of theradio waves and increase the transmission distance, the beamforming,massive multiple-input multiple-output (MIMO), Full Dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques are discussed in 5G communication systems. In addition, in 5Gcommunication systems, development for system network improvement isunder way based on advanced small cells, cloud Radio Access Networks(RANs), ultra-dense networks, device-to-device (D2D) communication,wireless backhaul, moving network, cooperative communication,Coordinated Multi-Points (CoMP), reception-end interference cancellationand the like. In the 5G system, Hybrid FSK and QAM Modulation (FQAM) andsliding window superposition coding (SWSC) as an advanced codingmodulation (ACM), and filter bank multi carrier (FBMC), non-orthogonalmultiple access (NOMA), and sparse code multiple access (SCMA) as anadvanced access technology have been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof Things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofEverything (IoE), which is a combination of the IoT technology and theBig Data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “Security technology” have been demanded forIoT implementation, a sensor network, a Machine-to-Machine (M2M)communication, Machine Type Communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing Information Technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, Machine Type Communication (MTC), andMachine-to-Machine (M2M) communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RadioAccess Network (RAN) as the above-described Big Data processingtechnology may also be considered to be as an example of convergencebetween the 5G technology and the IoT technology.

Meanwhile, a terminal (also referred to as user equipment (UE) or thelike) should be offered a service through a suitable core network (CN)for providing that service. This suitable core network may be referredto as a dedicated core network (DCN). Therefore, when a non-accessstratum (NAS) message is received from a terminal, a base station (alsoreferred to as evolved node B (eNodeB or eNB) or the like) shouldtransmit the NAS message to a mobility management entity (MME) containedin the DCN so that the terminal can be offered a service through theDCN. However, if any MME selected by the base station is not a dedicatedMME which is contained in the DCN, the base station is required toselect an MME again.

SUMMARY

In order to meet the above-mentioned need or the like, the presentinvention provides a method and apparatus for allowing a base station totransmit an NAS message to a dedicated MME through rerouting of the NASmessage when an MME receiving the NAS message is not the dedicated MME.

According to various embodiments of the present invention, a methodimplemented at a base station in a wireless communication systemincludes steps of receiving a non-access stratum (NAS) message from userequipment (UE); transmitting a first initial UE message having the NASmessage to a first mobility management entity (MME); receiving aredirection request message having the NAS message from the first MME;and transmitting a second initial UE message having the NAS message to asecond MME.

According to various embodiments of the present invention, a basestation in a wireless communication system includes a communication unitconfigured to perform communication with other network entity; and acontrol unit configured to control the communication unit to receive anon-access stratum (NAS) message from user equipment (UE), to transmit afirst initial UE message having the NAS message to a first mobilitymanagement entity (MME), to receive a redirection request message havingthe NAS message from the first MME, and to transmit a second initial UEmessage having the NAS message to a second MME.

According to various embodiments of the present invention, a methodimplemented at a mobility management entity (MME) in a wirelesscommunication system includes steps of receiving a first initial userequipment (UE) message having a non-access stratum (NAS) message from abase station; and transmitting a redirection request message having theNAS message when the MME fails to support a dedicated core networkaccording to UE usage type information, wherein if the redirectionrequest message is transmitted, a second initial UE message having theNAS message is transmitted to a dedicated MME.

According to various embodiments of the present invention, a mobilitymanagement entity (MME) in a wireless communication system includes acommunication unit configured to perform communication with othernetwork entity; and a control unit configured to control thecommunication unit to receive a first initial user equipment (UE)message having a non-access stratum (NAS) message from a base station,and to transmit a redirection request message having the NAS messagewhen the MME fails to support a dedicated core network according to UEusage type information, wherein if the redirection request message istransmitted, a second initial UE message having the NAS message istransmitted to a dedicated MME.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating the structure of a communication systemaccording to an embodiment of the present invention.

FIGS. 2A and 2B are flow diagrams illustrating a procedure in which UEregisters with a network.

FIG. 3A is a flow diagram illustrating an attach process of UE accordingto the first embodiment of the present invention.

FIG. 3B is a flow diagram illustrating an NAS message reroute processaccording to the first embodiment of the present invention.

FIG. 3C is a flow diagram illustrating a process of registering UE in anetwork through MME/SGSN according to the first embodiment of thepresent invention.

FIG. 4 is a flow diagram illustrating another NAS message rerouteprocess according to the first embodiment of the present invention.

FIG. 5 is a flow diagram illustrating a process in which the first MMEregisters UE in a network according to the first embodiment of thepresent invention.

FIG. 6 is a flow diagram illustrating a process in which eNodeBregisters UE in a network according to the first embodiment of thepresent invention.

FIG. 7 is a flow diagram illustrating a process in which HeNB GWregisters UE in a network according to the first embodiment of thepresent invention.

FIG. 8 is a block diagram illustrating a configuration of the first MMEaccording to the first embodiment of the present invention.

FIG. 9 is a block diagram illustrating a configuration of eNodeBaccording to the first embodiment of the present invention.

FIG. 10 is a block diagram illustrating a configuration of UE accordingto the first embodiment of the present invention.

FIG. 11 is a flow diagram illustrating a process in which UE appliesACDC in a TAU procedure according to the second embodiment of thepresent invention.

FIG. 12 is a flow diagram illustrating a process of applying ACDC in aTAU procedure according to the second embodiment of the presentinvention.

FIG. 13 is a flow diagram illustrating another process in which UEapplies ACDC in a TAU procedure according to the second embodiment ofthe present invention.

FIG. 14 is a flow diagram illustrating another process of applying ACDCin a TAU procedure according to the second embodiment of the presentinvention.

FIG. 15 is a block diagram illustrating a configuration of UE accordingto the second embodiment of the present invention.

FIG. 16A and FIG. 16B are flow diagrams illustrating a method forproviding an MBMS service according to the third embodiment of thepresent invention.

FIG. 17 is another flow diagram illustrating a method for providing anMBMS service according to the third embodiment of the present invention.

FIG. 18 is a block diagram illustrating a configuration of MME accordingto the third embodiment of the present invention.

FIG. 19 is a block diagram illustrating a configuration of MCE accordingto the third embodiment of the present invention.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be described withreference to the accompanying drawings. Through the drawings, the sameor similar reference numerals denote corresponding featuresconsistently. Additionally, well known functions and configurations maynot be described or illustrated in detail to avoid obscuring the subjectmatter of the present invention.

Also, embodiments of the present invention will be described hereinafterby mainly targeting Long-Term Evolution (LTE) and Evolved Packet Core(EPC), which are a Radio Access Network (RAN) and a Core Network (CN)defined as standards by the 3rd Generation Partnership Project (3GPP),the essential concept of this invention may be favorably applied to anyother communication system having a similar technical background withoutdeparting from the scope of this invention as will be apparent to thoseskilled in the art.

The present invention may be embodied in many different forms withoutchanging technical subject matters and essential features as will beunderstood by those skilled in the art. Therefore, embodiments set forthherein are exemplary only and not to be construed as a limitation.

In embodiments, all steps and messages are not a target for selectiveimplementation or omission. Additionally, in each embodiment, steps maynot be always performed in the order described and may be changed inorder. Similarly, delivery of messages may not be always performed inthe order described and may be changed in order. Each step and messagingmay be performed independently.

The whole or parts of exemplary contents in embodiments are provided topromote understanding by showing a detailed embodiment of thisinvention. Therefore, the detailed contents may be regarded asexpressing a part of method and apparatus proposed by this invention.Namely, with regard to such contents, a syntax-based approach may bemore desirable than a semantics-based approach. While this disclosurehas been particularly shown and described with reference to an exemplaryembodiment thereof, it will be understood by those skilled in the artthat various changes in form and details may be made therein withoutdeparting from the spirit and scope of this disclosure as defined by theappended claims.

The present invention may be embodied in many different forms and shouldnot be construed as limited to the embodiments set forth herein. Rather,the disclosed embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of this inventionto those skilled in the art. The principles and features of the presentinvention may be employed in varied and numerous embodiments withoutdeparting from the scope of the invention.

The terms used in the present disclosure are only used to describespecific various embodiments, and are not intended to limit the presentdisclosure. As used herein, the singular forms are intended to includethe plural forms as well, unless the context clearly indicatesotherwise.

It will be understood that each block of the flowchart illustrations,and combinations of blocks in the flowchart illustrations, can beimplemented by computer program instructions. These computer programinstructions can be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which are executed via the processor of the computer or otherprogrammable data processing apparatus, create means for implementingthe functions specified in the flowchart block or blocks. These computerprogram instructions may also be stored in a computer usable orcomputer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer usable orcomputer-readable memory produce an article of manufacture includinginstruction means that implement the function specified in the flowchartblock or blocks. The computer program instructions may also be loadedonto a computer or other programmable data processing apparatus to causea series of operational steps to be performed on the computer or otherprogrammable apparatus to produce a computer implemented process suchthat the instructions that are executed on the computer or otherprogrammable apparatus provide steps for implementing the functionsspecified in the flowchart block or blocks.

And each block of the flowchart illustrations may represent a module,segment, or portion of code, which comprises one or more executableinstructions for implementing the specified logical function(s). Itshould also be noted that in some alternative implementations, thefunctions noted in the blocks may occur out of the order. For example,two blocks shown in succession may in fact be executed substantiallyconcurrently or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved.

The term “unit”, as used herein, may refer to a software or hardwarecomponent or device, such as a Field Programmable Gate Array (FPGA) orApplication Specific Integrated Circuit (ASIC), which performs certaintasks. A unit may be configured to reside on an addressable storagemedium and configured to execute on one or more processors. Thus, amodule or unit may include, by way of example, components, such assoftware components, object-oriented software components, classcomponents and task components, processes, functions, attributes,procedures, subroutines, segments of program code, drivers, firmware,microcode, circuitry, data, databases, data structures, tables, arrays,and variables. The functionality provided for in the components andmodules/units may be combined into fewer components and modules/units orfurther separated into additional components and modules.

First Embodiment

FIG. 1 is a diagram illustrating the structure of a communication systemaccording to an embodiment of the present invention. According to thisembodiment, the communication system may be an LTE-based mobilecommunication system.

Referring to FIG. 1, as shown, a wireless access network of the LTEmobile communication system may be formed of an evolved Node B (alsoreferred to as eNB, a base station, E-UTRAN, etc.) 130, a mobilitymanagement entity (MME) 150, and a serving gateway (S-GW) 140.

User equipment (also referred to as UE, a terminal, etc.) 100 may accessan external network through the eNB 130, the S-GW 140, and a PDN gateway(P-GW) 160. In order to transmit or receive data through the P-GW, theUE should create a PDN connection, which may include at least one EPSbearer.

An application function (AF) 110 is an apparatus that exchangesapplication-related information with a user at the level of application.

A policy charging and rules function (PCRF) 120 is an apparatus thatcontrols a policy associated with user's quality of service (QoS). Apolicy and charging control (PCC) rule corresponding to the above policyis delivered and applied to the P-GW 160.

The eNB 130 is a radio access network (RAN) node and corresponds to RNCof a UTRAN system and to BSC of a GERAN system. The eNB 130 is connectedto the UE 100 in a radio channel and performs a role similar to that ofthe existing RNC/BSC.

Since all user traffics including real-time services such as a voiceover internet protocol (VoIP) are offered through a shared channel inLTE, an apparatus for collecting status information of UEs 100 andperforming scheduling is needed. The eNB 130 is in charge of this.

The S-GW 140 is an apparatus that offers a data bearer, and creates orremoves the data bearer under the control of the MME 150.

The MME 150 is an apparatus that performs various control functions, anda single MME 150 may be connected with a plurality of eNBs. In thisinvention, a certain MME newly accessed by the UE 100 is referred to asa new MME 150. Also, an MME accessed before attachment and acorresponding network entity are referred to as old MME/SGSN 152. Andalso, an MME accessed by the UE 100 to access a dedicated core networkis referred to as a dedicated MME 154.

The PCRF 120 is an entity that controls QoS of traffic and charging.

Meanwhile, as mentioned above, the LTE system supports interworking withany access network other than 3GPP as well as E-UTRAN. If any non-3GPPaccess network is interworked, the non-3GPP access network may beconnected to the PGW 160 directly or through an additional ePDG. Forprocessing subscriber information or authentication with regard to thenon-3GPP access network, a home subscriber server (HSS) 170 and anauthentication, authorization and accounting (AAA) server may exchangeinformation with each other and may also be realized as a signal entity.The term ePDG is exemplarily used for convenience. Even in case thenon-3GPP access network is connected to the PGW directly or connectedthrough any node, e.g., the S-GW, other than ePDG, an embodimentdisclosed herein may be applied without any considerable modification.

FIGS. 2A and 2B are flow diagrams illustrating a procedure in which UEregisters with a network.

This registration procedure is also referred to as a network attachment.During this procedure, a default EPS bearer is created for always-on IPconnectivity.

Referring to FIG. 2A, at step 201, the UE 100 may transmit an attachrequest message to the eNB 130. At step 202, the eNB 130 that receivesthe attach request message may transmit the attach request message to anew MME 150.

The new MME 150 that receives the attach request message may transmit anidentification request message for identifying UE to an old MME orserving GPRS support node (SGSN) 152 at step 203 a and may receive anidentification response message from the old MME/SGSN 152 at step 203 b.If the old MME/SGSN 152 and the new MME 150 fail to identify the UE 100,the new MME 150 may transmit an identity request message to the UE 100at step 204 a and may receive an identity response message containing aninternational mobile subscriber identity (IMSI) from the UE 100 at step204 b.

If context of the UE 100 does not exist in the network, the UE 100, thenew MME 150 and the HSS 170 may perform an authentication/securityprocedure at step 205 a.

After the authentication/security procedure, at step 205 b, the UE 100may transmit a ciphered identity request message to the new MME 150 andmay receive a ciphered identity response message from the new MME 150.This step may be performed together with the authentication/securitystep 205 a.

Thereafter, if the UE 100 sets a ciphered options transfer flag in theattach request message, the new MME 150 may transmit a ciphered optionsrequest message to the UE 100 at step 206 a and may receive a cipheredoptions response message from the UE 100 at step 206 b.

If there is activated bearer context for the UE 100 in the new MME 150,the new MME 150 may transmit a delete session request message to theS-GW 140 at step 207 a. Then the S-GW 140, the P-GW 160 and the PCRF 120may terminate a session at step 207 b, and the S-GW 140 may transmit adelete session response message to the new MME 150 at step 207 c.

If the MME is changed after the final detach, or if there is no validsubscriber context for the UE in the MME, the new MME 150 may transmitan update location request message to the HSS 170 at step 208. Then theHSS 170 may transmit a cancel location message to the old MMS/SGSN 152at step 209 a and may receive a cancel location ACK message from the oldMMS/SGSN 152 at step 209 b.

If there is activated bearer context for the UE 100 in the old MME/SGSN152, the old MME/SGSN 152 may transmit a delete session request messageto the S-GW 140 at step 210 a. Then the S-GW 140, the P-GW 160 and thePCRF 120 may terminate a session at step 210 b, and the S-GW 140 maytransmit a delete session response message to the old MME 150 at step210 c. Thereafter, the HSS 170 may transmit an update location ACKmessage to the new MME 150 at step 211.

FIG. 2B shows steps after the new MME 150 receives the update locationACK message in FIG. 2A.

Referring to FIG. 2B, at step 212, the new MME 150 may transmit a createsession request message to the S-GW 140. Then the S-GW 140 may create asession with the P-GW 160 and the PCRF 120 at steps 213, 214 and 215,and may transmit a create session response message to the new MME 150 atstep 216.

Thereafter, the new MME 150 may transmit an initial context setuprequest message, by inserting an attach accept message therein, to theeNB 130 at step 217.

The eNB 130 that receives this may transmit a radio resource control(RRC) connection reconfiguration message to the UE 100 at step 218. Ifthe UE 100 transmits an RRC connection reconfiguration complete messageto the eNB 130 at step 219, the eNB 130 may transmit an initial contextsetup response message to the new MME 150 at step 220.

Thereafter, the UE 100 may transmit a direct transfer message containingan attach complete message to the eNB 130 at step 221, and the eNB 130may deliver the attach complete message to the new MME 150 at step 222.

The new MME 150 that receives the initial context response message andthe attach complete message may transmit a modify bearer request messageto the S-GW 140 at step 223 a. The S-GW 140 and the P-GW 160 may performa bearer modification at steps 223 b and 223 c, and the S-GW 140 maytransmit a modify bearer response message to the new MME 150 at step224.

Thereafter, if a mobile equipment identity of the UE 100 is changed, thenew MME 150 may transmit a notify request message to the HSS 170 at step225 and may receive a notify response message from the HSS 170 at step226.

Meanwhile, when the UE 100 transmits the attach request message to theeNB 130 at step 201, this attach request message may be contained in anRRC connection setup complete message that is transmitted from the UE tothe eNB. Also, at step 202, the eNB may transmit an initial UE message,which is an S 1-MME control message containing the attach requestmessage, to the new MME 150.

At this time, a core network to which the new MME 150 receiving theattach request message from the UE 100 belongs may be not identical to adedicated core network (DCN) of the UE. This dedicated core network maybe used for allowing an operator to offer a particular function or forseparating specific UE or subscriber. For example, the dedicated corenetwork may be used for separating subscribers for machine-to-machine(M2M) communication or separating subscribers of a specific company.

The UE needs to access the DCN corresponding to a usage type thereof andthen be offered a suitable service. However, if the eNB 130 fails toselect the DCN, it may be required to deliver a message, transmitted tothe MME/SGSN 150, to a dedicated MME/SGSN 154 contained in the DCN suchthat the UE can be serviced by the DCN. Therefore, described hereinafteris a method for allowing the UE to be offered a service from the DCN byrerouting an NAS message when the eNB fails to select the DCN.

FIG. 3A is a flow diagram illustrating an attach process of UE accordingto the first embodiment of the present invention. Steps which are notdescribed herein may follow, partially or totally, a normal EPS attachprocedure.

Referring to FIG. 3A, the new MME/SGSN 150 may receive an attach requestmessage from the UE 100 through the eNB 130 at steps 201 and 202.Although the attach request message is used exemplarily herein, an NASmessage including a tracking area update (TAU) message, a routing areaupdate (RAU) message, or the like may be used alternatively. The attachrequest message may be delivered to the eNB 130 from the UE 100 in theform of being contained in an RRC message and also delivered to theMME/SGSN 150 from the eNB 130 in the form of being contained in aninitial UE message (an RAN message).

The attach request message may contain a globally unique temporary UEidentity (GUTI)/P-temporary mobile subscriber identity (P-TMSI) and/oradditional GUTI/P-TMSI. In case a GUTI is created from a P-TMSI and arouting area identifier (RAI) (this GUTI may be referred to as a mappedGUTI), or in case a P-TMSI is created from a GUTI (this P-TMSI may bereferred to as a mapped P-TMSI), the attach request message may containadditional GUTI/P-TMSI. If the DCN is not considered, the additionalGUTI/P-TMSI may be used for checking whether there is context of UEidentified using such additional GUTI/P-TMSI in the new MME/SGSI 150.

The new MME 150 that receives the attach request message may transmit anidentification request message to the old MME/SGSN 152 at step 203 a andmay receive an identification response message having MM context fromthe old MME/SGSN 152 at step 203 b. The identification response messagehaving MM context may contain UE usage type information. In embodimentsdisclosed herein, the UE usage type information may refer to informationabout UE. Specifically, the UE usage type information may be used forsteering the UE to a suitable DCN. Namely, the UE usage type informationmay be information that indicates a usage character of the UE. A mobilecommunication network operator may deploy a suitable DCN for such a UEusage character.

The UE usage type information may be delivered in the form of beingcontained in the MM context or as an information element which isindependent of the MM context. As will be described below in detail, asuitable DCN for serving the UE 100 may be identified from this UE usagetype information, and the MME 150 may transmit suitable information tothe eNB 130 so that the eNB 130 can retransmit the attach requestmessage to a suitable DCN. Alternatively, contrary to this, the UE usagetype information and/or any helpful information to select a DCN may becontained in an RRC message having the attach request message and thensent to the eNB 130.

At step 303 a, the new MME/SGSN 150 that receives the identificationresponse message may have already obtained the UE usage type informationof the UE 100, and thus can determine whether to support a DCN dependingon the UE usage type information of the UE 100.

As a result, if it is determined that the new MME/SGSN 150 fails tosupport a DCN of the UE, the new MME/SGSN 150 may reroute (also referredto as redirect) the attach request message such that the UE can receivea service from a suitable dedicated MME/SGSN 154.

As discussed above, the UE usage type information may be deliveredthrough the identification response message transmitted from the oldMME/SGSN 152 to the new MME 150 at step 203 b or through an updatelocation acknowledgement message transmitted from the HSS 170 to the newMME 150 at step 211. The update location acknowledgement message is amessage delivered to the new MME 150 from the HSS 170 at step 211, andthe HSS 170 may deliver subscription data to the new MME 150. At thistime, the UE usage type information may be contained in the subscriptiondata or delivered separately from the subscription data. Therefore, aredirection process of a non-access stratum (NAS) message to bedescribed below may be performed after step 203 b or after step 211.Also, the HSS 170 may deliver the UE usage type information to the MME150 at step 205 a.

Although an example of rerouting the attach request message is describedabove, this is not considered as a limitation of the present invention.Namely, this invention relates to a process of rerouting the NASmessage, and this rerouting process may be performed during the attachprocedure, the TAU procedure, and the RAU procedure.

FIG. 3B is a flow diagram illustrating an NAS message reroute processaccording to the first embodiment of the present invention.

Referring to FIG. 3B, in case the new MME/SGSN 150 that becomes aware ofthe UE usage type applied to the UE 100 through step 203 b, step 205 a,and/or step 211 fails to support the DCN of the UE 100, the new MME/SGSN150 may deliver, at step 300, a message for rerouting the NAS message toMME/SGSN corresponding to characteristics of UE. Herein, the MME/SGSNcorresponding to characteristics of UE may refer to the dedicatedMME/SGSN 154 located in the DCN corresponding to the UE usage typeinformation of UE. In this case, a message (hereinafter, referred to asa redirection message) for rerouting the NAS message may be defined as anew RAN message named a reroute command message, reroute message, or areroute NAS request message.

The redirection message (i.e., the RAN message) may contain at least oneof MME UE S1AP ID, eNB UE S1AP ID, (revised) NAS-PDU (Protocol DataUnit), GUTI, GUMMEI (Globally Unique MME Identity), MMEGI (MME GroupIdentifier) or Null NRI (Network Resource Identifier)/SGSN group ID,GUMMEI type, S-TMSI (SAE Temporary Mobile Subscriber Identity), TAI(Tracking Area Identity) and RRC establishment cause, additionalGUTI/P-TMSI, and information delivered to the MME/SGSN 150 by the eNB130.

MME UE S1AP ID is an identifier allocated by the new MME/SGSN 150 toidentify the UE 100 on the S1 interface. Also, eNB UE S1AP ID is anidentifier allocated by the eNB 130 to identify the UE 100 on the S1interface. Using eNB UE S1AP ID, the eNB 130 may determine which UEneeds redirection. This eNB UE S1AP ID contained in the redirectionmessage by the new MME/SGSN 150 may be identical to eNB UE S1AP IDcontained in an S1 message received through at least one of steps 202,204 b, 205 a, 205 b and 206 b.

NAS-PDU contained in the redirection message may be an NAS messagereceived from the eNB. For example, the NAS message may be an attachrequest message. This attach request message may be identical to theattach request message received by the new MME/SGSN 150 at step 202 or aslightly revised version thereof. For example, the EPS mobile identityfield of the attach request message may be revised to GUTI allocated bythe new MME/SGSN 150. In another example, NAS-PDU may not be revised andGUTI may be delivered as an independent information element. In thiscase, the eNB 130 may deliver GUTI, received at step 300, as anindependent information element to the dedicated MME/SGSN 154 when aninitial UE message or uplink NAS transport message is transmitted atstep 310.

GUMMEI, MMEGI or Null-NRI/SGSN group ID, GUMMEI type, S-TMSI, andadditional GUTI/P-TMSI are information that may be used for the eNB 130to select the dedicated MME/SGSN 154. The new MME/SGSN 150 may set atleast one of GUMMEI, MMEGI or Null-NRI/SGSN group ID, GUMMEI type, andS-TMSI as a value associated with the dedicated MME/SGSN 154 and thentransmit it to the eNB 130.

MMEGI or Null-NRI/SGSN group ID may be used to identify a DCN in a PLMN(Public Land Mobile Network).

GUMMEI may directly indicate the dedicated MME 154. GUMMEI may be formedof a PLMN identifier, MMEGI, and MMEC. The new MME may set a PLMNidentifier as a serving PLMN of the UE 100 (namely, identical to a PLMNpart of TAI), set MMEGI as a value corresponding to a dedicated MMEgroup, and set MMEC (MME Code) as a value corresponding to MMEC of thenew MME. The eNB 130 may select a dedicated MME group by using PLMN andMMEGI, and also select dedicated MME by referring to MMEC. In anotherexample, GUMMEI may be a GUMMEI part of additional GUTI contained in theattach request message. MMEGI may be information corresponding to adedicated MME group. This may be MMEGI included in MMEI (MME Identifier)contained in GUMMEI of additional GUTI contained in the attach requestmessage.

TAI and RRC establishment cause may be information received from the eNB130 together with the attach request message by the new MME 150.

Additional GUTI/P-TMSI may be contained in the reroute NAS messagerequest only in case the attach request message received by the MME/SGSN150 contains the additional GUTI/P-TMSI. Namely, if additionalGUTI/P-TMSI is contained in the attach request message received at step202, the MME/SGSN 150 may insert the additional GUTI/P-TMSI into thereroute NAS message request to be transmitted at step 300.

The eNB 130 that receives at least one kind of information mentionedabove may insert the TAI and/or RRC establishment cause, received atstep 300, into a message to be transmitted to the dedicated MME 154 atstep 310. The new MME 150 may also transmit additional GUTI contained inthe attach request message. This additional GUTI may be delivered onlywhen the new MME 150 fails to find UE context by means of additionalGUTI and when old GUTI denotes that GUTI is mapped with P-TMSI(P-temporary mobile subscriber identity) and RAI (routing areaidentifier).

The information delivered to the new MME/SGSN 150 by the eNB 130, whichis contained in a message delivered by the eNB 130 at step 300, may meaninformation contained in the first initial UE message delivered by theeNB 130 at step 202. The information may include all or part ofinformation delivered at step 202. According to 3GPP Release 13, thefirst initial UE message is formed as shown in Table 1.

TABLE 1 IE type and Semantics Assigned IE/Group Name Presence referencedescription Criticality Criticality Message Type M YES ignore eNB UES1AP ID M YES reject NAS-PDU M YES reject TAI M Indicating the YESreject Tracking Area from which the UE has sent the NAS message. E-UTRANCGI M Indicating the E- YES ignore UTRAN CGI from which the UE has sentthe NAS message. RRC M YES Ignore Establishment Cause S-TMSI O YESreject CSG Id O YES reject GUMMEI O YES reject Cell Access Mode O YESreject GW Transport O Transport Indicating GW YES ignore Layer AddressLayer Transport Layer Address Address if the GW is collocated with eNB.Relay Node O Indicating a relay YES reject Indicator node. GUMMEI Type OENUMERATED YES ignore (native, mapped, . . . ) Tunnel O TunnelIndicating HeNB's YES ignore Information for Information Local IPAddress BBF assigned by the broadband access provider, UDP port Number.SIPTO L-GW O Transport Indicating SIPTO YES ignore Transport Layer LayerL-GW Transport Address Address Layer Address if the SIPTO L-GW iscollocated with eNB. LHN ID O YES ignore MME Group ID O YES ignore

Among various kinds of information shown in Table 1, certain informationmay be known semipermanently to the eNB 130 and certain information mayneed to be received again since the eNB 130 has already received it fromthe UE 100 and then stores it. For example, GW Transport Layer Addressis inherent information of the eNB 130 and thus known to the eNB 130.Also, RRC Establishment Cause is information received from the UE 100 atstep 201.

However, since backhaul is not very congested in general, theredirection message delivered at step 300 may contain the first initialUE message completely for simplification of the operation of theMME/SGSN 150.

Additionally, the redirection message may contain other S1 message,e.g., an uplink NAS transport message. This is for encompassing variouscases in which the UE delivers the NAS message. For example, the UE mayregister a new location in the MME/SGSN 150 after handover. In thiscase, since the NAS message for location registration is not the initialS1 message for the UE, the NAS message may be delivered through theuplink NAS transport message rather than through the initial UE message.In this case, the redirection message delivered at step 300 may containthe uplink NAS transport message.

For selecting the dedicated MME/SGSN 154, the eNB 130 may use at leastone of MMEGI or Null-NRI/SGSN group ID and additional GUTI/P-TMSI whichare received at step 300. Specifically, the eNB 130 may select MME/SGSNin a DCN indicated by MMEGI or Null-NRI/SGSN group ID. If additionalGUTI/P-TMSI identifies MME/SGSN in the DCN indicated by MMEGI orNull-NRI/SGSN group ID, MME/SGSN identified by additional GUTI/P-TMSImay be selected.

The eNB 130 that selects the dedicated MME/SGSN 154 may transmit thesecond initial UE message or uplink NAS transport message to thededicated MME/SGSN 154 at step 310. Herein, while an initial UE messagetransmitted to the new MME by the eNB at step 202 is referred to as thefirst initial UE message, an initial UE message transmitted to thededicated MME by the eNB at step 310 is referred to as the secondinitial UE message. If it is not possible to find selectable MME/SGSN ina DCN identified by means of MMEGI or Null-NRI/SGSN group ID, the eNB130 may select MME/SGSN in the default DCN or select again the MME/SGSN150.

The above discussion may be applied to only a network which is notshared by several PLMNs. In a network shared by several PLMNs, a DCN maybe selected using the following method.

The eNB 130 may select the dedicated MME/SGSN 154 by using a PLMN (CNoperator) selected by the UE 100 and at least one of MMEGI orNull-NRI/SGSN group ID and additional GUTI/P-TMSI which are received atstep 300. Specifically, the eNB 130 may select MME/SGSN in a DCNindicated by MMEGI or Null-NRI/SGSN group ID within the PLMN selected bythe UE 100. If additional GUTI/P-TMSI identifies MME/SGSN in the DCNindicated by MMEGI or Null-NRI/SGSN group ID within the PLMN selected bythe UE 100, the eNB 130 may select MME/SGSN identified by additionalGUTI/P-TMSI. In this case, the PLMN in the additional GUTI/P-TMSI may beignored.

Namely, in case the eNB 130 receives additional GUTI/P-TMSI in thenetwork shared by several PLMNs, the eNB 130 may select (if possible) acore network indicated by a combination of the following information:

-   -   PLMN selected by the UE 100;    -   MMEGI or Null-NRI/SGSN group ID; and    -   Most significant 8 bits of MMEC or NRI in additional        GUTI/P-TMSI.

In this case, a method for identifying the PLMN selected by the UE 100at the eNB 130 may include at least one of the followings.

The eNB 130 may store and use information about the PLMN selected by theUE 100 by receiving it from the UE 100 at step 201. Also, the eNB 130may identify the PLMN selected by the UE 100 from information containedin the redirection message (S1 message) received at step 300. In thelatter case, the eNB 130 may extract a PLMN ID part of TAI informationin the redirection message (S1 message) and thereby identify the PLMNselected by the UE.

The eNB 130 that selects the dedicated MME/SGSN 154 may transmit thesecond initial UE message or uplink NAS transport message to thededicated MME/SGSN 154 at step 310. If it is not possible to findselectable MME/SGSN in a DCN identified by means of MMEGI orNull-NRI/SGSN group ID, the eNB 130 may select MME/SGSN in the defaultDCN or select again the MME/SGSN 150. Herein, the second initial UEmessage (S1 message) delivered at step 310 may be the S1 messagecontained in the redirection message received at step 300.

The second initial UE message of step 310 may include informationcontained in the first initial UE message transmitted at step 202 andfurther include at least one of MME UE S1AP ID, NAS-PDU, GUTI, S-TMSI,and additional GUTI. Namely, the second initial UE message delivered atstep 310 may include the NAS message (e.g., the attach request message)delivered to the MME/SGSN 150 at step 202. The dedicated MME 154 thatreceives this may check, using at least one of additional GUTI andS-TMSI, whether there is context of the UE therein. If there is contextof the UE, the existing UE context may be reused without obtainingcontext from any other node (the new MME 150 and/or the HSS 170). Forexample, context of the UE may be used for mobility management of theUE. At least one of NAS-PDU, GUTI, MME UE S1AP ID, and S-TMSI deliveredat step 300 may be also delivered at step 320 through step 310.

Thereafter, at step 320, the new MME 150 may receive an MM contextrequest message from the dedicated MME 154. At this time, the MM contextrequest message may be an identification request message. The dedicatedMME 154 may transmit the attach request message received from the newMME 150 through the eNB 130. Then, the new MME 150 may verify the attachrequest message and adjust an uplink NAS count in MME at step 303 a inorder to prevent errors at verification step. For example, even in caseverification is made, the uplink NAS count may be not increased. Theoperation related to step 303 a may be performed after step 205 a.

When the MME that sends the identification request at step 320 is thededicated MME 154, and/or when the reroute command message has beenalready sent for the UE identified by means of information contained inthe identification request message, the new MME 150 may skipverification through NAS-PDU. In another example, when an indicator forindicating a verification skip is delivered at step 320, the new MME 150may skip the verification step. As discussed above, verification isperformed in case the NAS count is adjusted at step 303 a. The new MME150 may identify the UE 100 by using at least one of GUTI, MME UE S1APID, and S-TMSI contained in the identification request message forrequesting MM context, and then deliver MM context corresponding to theUE by using an identification response message at step 340.

Thereafter, steps 204 to 211 shown in FIG. 2 may be performed. Thedifference is that the dedicated MME 154 is involved instead of the newMME 150.

FIG. 3C is a flow diagram illustrating a process of registering UE in anetwork through MME/SGSN according to the first embodiment of thepresent invention.

Referring to FIG. 3C, steps 312 to 326 shown in FIG. 3C may be identicalto steps 212 to 226 previously discussed in FIG. 2B. However, contraryto FIG. 2B, the process of FIG. 3C involves the dedicated MME/SGSN 154instead of the new MME 150 in the registration procedure. Details willbe omitted herein since the same is discussed in FIG. 2B. Using theprocess discussed in FIGS. 3A to 3C, the UE can be offered a servicethrough the DCN. In this case, the UE 100 may transit a message to acore network through two or more eNBs rather than through a single eNBonly. For example, this message may be transmitted to the core networkthrough HeNB, HeNB GW, MME or UE, relay node, donor eNB, and MME.

FIG. 4 is a flow diagram illustrating another NAS message rerouteprocess according to the first embodiment of the present invention.

Referring to FIG. 4, the NAS message reroute process in case HeNB (homeeNB)/DeNB (donor eNB) and HeNB GW (HeNB gateway)/RN (relay node) areincluded is shown.

The new MME may transmit the redirection message to the HeNB GW/DeNB atstep 400. The redirection message may mean a message for rerouting theNAS message and may include a reroute command or a reroute NAS requestmessage.

Considering that a UE-associated message is not terminated at the HeNBGW/DeNB except for unusual circumstance, steps 410 and 420 may beperformed in spite of inefficiency in signaling. Also, in case aninitial UE message needs revision, steps 410 and 420 may be performed.

Specifically, the HeNB GW/DeNB may transmit a reroute command to theHeNB/RN at step 410 and receive a response message (S1 (NAS EMM)) atstep 420.

However, if the message delivered at step 400 contains the entireinformation of the attach request message delivered at step 202 (e.g.,in case the first initial UE message delivered at step 202 is completelycontained in the redirection message delivered at step 400), the HeNB GWand/or DeNB may perform a message redirection without performing steps410 and 420 even though not storing information received from the HeNBand/or relay node. Therefore, in this case, the HeNB GW/DeNB may nottransmit the reroute command message to the HeNB.

Additionally, step 400 may correspond to step 300 in FIG. 3.Specifically, information contained in the redirection message may beidentical to information contained in the redirection messagetransmitted at step 300.

Thereafter, the HeNB GW may select a DCN at step 430. This step 430 maycorrespond to a process of selecting a core network node performed bythe eNB 300 after step 300 in FIG. 3.

The HeNB GW that selects the DCN may transmit the S1 message to thededicated MME at step 440. The step 440 (and step 420) may correspond tostep 310 in FIG. 3, and detailed description thereof will be omitted.

FIG. 5 is a flow diagram illustrating a process in which the first MMEregisters UE in a network according to the first embodiment of thepresent invention.

Referring to FIG. 5, the first MME may receive an initial UE messagefrom the eNB at step 510. The initial UE message may contain an NASmessage received from the UE by the eNB. The NAS message may betransmitted to the eNB from the UE in the form of being contained in anRRC message, and then transmitted to the first MME in the form of beingcontained in the initial UE message.

The first MME that receives the first message may transmit anidentification request message to the second MME at step 520. Also, thefirst MME may receive an identification response message for theidentification request message at step 530.

The identification response message may contain UE usage typeinformation. The UE usage type information is information for indicatinga usage type of UE and may be included in the MM context contained inthe identification response message or may be transmitted as aninformation element which is independent of the MM context.

Additionally, the UE usage type information may be contained in anupdate location ACK message received from the HSS, and the followingsteps may be performed after the eNB receives the update location ACKmessage. This embodiment will be discussed regarding an example in whichthe UE usage type information is contained in the identificationresponse message.

At step 540, the first MME that receives the identification responsemessage may identify a DCN corresponding to the UE usage typeinformation and then may check whether the first MME can support theDCN.

As the result of check, if it is determined that the first MME cansupport the DCN, the first MME may perform a subsequent networkregistration process of UE at step 550.

As the result of check, if it is determined that the first MME cannotsupport the DCN, the first MME may enable the UE to be serviced from asuitable dedicated MME through redirection of the attach requestmessage.

Therefore, at step 560, the first MME may transmit a redirection messageto the eNB so as to reroute the attach request message. At this time,the redirection message may include a reroute command message or areroute NAS request message.

The redirection message may have at least one of MME UE S1AP ID, eNB UES1AP ID, (revised) NAS-PDU (Protocol Data Unit), GUTI, GUMMEI (GloballyUnique MME Identity), MMEGI (MME Group Identifier) or Null NRI (NetworkResource Identifier)/SGSN group ID, GUMMEI type, S-TMSI (SAE TemporaryMobile Subscriber Identity), TAI (Tracking Area Identity) and RRCestablishment cause, additional GUTI/P-TMSI, and information deliveredto the MME/SGSN by the eNB.

NAS-PDU contained in the redirection message may include an NAS message.This embodiment uses an attach request message as the NAS message.Namely, the first MME may insert the received attach request message inthe redirection message and then transmit it to the eNB. Also, the firstMME may insert the attach request message with partially revisedinformation in the redirection message and then transmit it to the eNB.

Additionally, the redirection message may contain totally the initial UEmessage received from the eNB.

Details of information contained in the redirection message arediscussed earlier in FIG. 3B, so the repetition is omitted herein.

The first MME that transmits the redirection message may receive anidentification request message from the dedicated MME at step 570. Theidentification request message may have the attach request message.

The first MME that receives the identification request message may checkor verify the attach request message at step 580 and then adjust an NAScount in the first MME in order to prevent errors at the check orverification step. For example, even in case the attach request messageis checked or verified, the uplink NAS count may be not increased.

Additionally, the first MME may identify the UE by using at least one ofGUTI, MME UE S1AP ID, and S-TMSI which are contained in theidentification request message. Then, at step 590, using anidentification response message, the first MME may transmit MM contextcorresponding to the identified UE to the dedicated MME.

FIG. 6 is a flow diagram illustrating a process in which eNodeBregisters UE in a network according to the first embodiment of thepresent invention.

Referring to FIG. 6, the eNB may receive an NAS message contained in anRRC message at step 610. Since the NAS message may include an attachrequest message, a TAU message, an RAU message, etc., this process maybe performed during an attach procedure, a TAU procedure, or an RAUprocedure.

The eNB that receives the NAS message may transmit the first initial UEmessage having the NAS message to the first MME at step 620. In thiscase, since information contained in the first initial UE message isdiscussed earlier in FIG. 3B, the repetition is omitted herein.

If the first MME is not MME contained in the DCN, the first MME maytransmit a redirection message for rerouting the NAS message to the eNB.

Therefore, at step 630, the eNB may receive the redirection message forrerouting the NAS message.

The redirection message may have at least one of MME UE S1AP ID, eNB UES1AP ID, (revised) NAS-PDU (Protocol Data Unit), GUTI, GUMMEI (GloballyUnique MME Identity), MMEGI (MME Group Identifier) or Null NRI (NetworkResource Identifier)/SGSN group ID, GUMMEI type, S-TMSI (SAE TemporaryMobile Subscriber Identity), TAI (Tracking Area Identity) and RRCestablishment cause, additional GUTI/P-TMSI, and information deliveredto the MME/SGSN by the eNB.

The eNB that receives the redirection message may select the second MMEby using information contained in the redirection message at step 640.In this case, the second MME may refer to a dedicated MME located in theDCN.

A method for selecting the second MME by using information contained inthe redirection message is as follows.

The first MME may set, as a value associated with the dedicated MME/SGSN154, at least one of GUMMEI, MMEGI or Null-NRI/SGSN Group ID, GUMMEIType, and S-TMSI and transmit it to the eNB. Then the eNB may select thededicated MME by using information set as the value associated with thededicated MME. MMEGI or Null-NRI/SGSN Group ID may be used to identify aDCN in a PLMN. GUMMEI may directly indicate the dedicated MME.Specifically, GUMMEI may be formed of a PLMN identifier, MMEGI, andMMEC. In this case, a PLMN identifier may be set as a serving PLMN ofthe UE 100 (namely, identical to a PLMN part of TAI at step 102), MMEGImay be set as a value corresponding to a dedicated MME group, and MMEC(MME Code) may be set as a value corresponding to MMEC of the first MME.Therefore, the eNB may select a dedicated MME group by using a PLMNidentifier and MMEGI, and then select a dedicated MME by referring toMMEC.

Additionally, the eNB may select MME/SGSN in the DCN indicated by MMEGIor Null-NRI/SGSN Group ID. If additional GUTI/P-TMSI identifies MME/SGSNin the DCN indicated by MMEGI or Null-NRI/SGSN Group ID, the eNB mayselect MME/SGSN identified by additional GUTI/P-TMSI.

Meanwhile, in a network shared by several PLMNs, a DCN may be selectedusing the following method.

The eNB may select a dedicated MME by using at least one of PLMN, MMEGIor Null-NRI/SGSN Group ID, and additional GUTI/P-TMSI which are selectedby the UE. The eNB may select MME/SGSN in the DCN indicated by MMEGI orNull-NRI/SGSN Group ID in PLMN selected by the UE. If additionalGUTI/P-TMSI identifies MME/SGSN in the DCN indicated by MMEGI orNull-NRI/SGSN Group ID, the eNB may select MME/SGSN identified byadditional GUTI/P-TMSI. Namely, in case the eNB receives additionalGUTI/P-TMSI, the eNB may select a core network by considering PLMN,MMEGI or Null-NRI/SGSN Group ID, and most significant 8 bits of MMEC orNRI in additional GUTI/P-TMSI which are selected by the UE. In thiscase, PLMN in additional GUTI/P-TSMI may be ignored.

A method in which the eNB identifies PLMN selected by the UE may be amethod of storing PLMN selected by and received from the UE and thenusing stored information, or a method of using PLMN contained in theredirection message and selected by the UE.

In case of using information contained in the redirection message, theeNB may identify PLMN selected by the UE by extracting PLMN ID of TAIinformation contained in the redirection message.

Selection of DCN and dedicated MME by the eNB may be similar to thatdiscussed in FIG. 3B.

The eNB that selects the dedicated MME may transmit the second initialUE message containing an NAS message to the dedicated MME at step 650.In this case, the second initial UE message may include the entireinformation contained in the redirection message. Also, the eNB maytransmit an uplink NAS transport message to the dedicated MME. If it isnot possible to find selectable MME in a DCN, the eNB may select MME inthe default DCN or select again the MME.

Using the above-discussed process, the eNB may enable the UE to beoffered service through a DCN.

FIG. 7 is a flow diagram illustrating a process in which HeNB GWregisters UE in a network according to the first embodiment of thepresent invention.

Referring to FIG. 7, the first MME that identifies a UE usage type maytransmit a redirection message to HeNB GW in case of failing to supporta DCN corresponding to the UE usage type. Details are similar todiscussed above, so the repetition is omitted herein.

Therefore, the HeNB GW may receive the redirection message at step 710.The redirection message may include a reroute command or a reroute NASrequest message.

In this case, the redirection message may include an NAS messagereceived from the UE and delivered to the first MME.

Since a UE-associated message is not terminated at the HeNB GW/DeNBexcept for unusual circumstance, the HeNB GW may transmit theredirection message to the HeNB at step 720 in spite of inefficiency insignaling. Also, the HeNB GW may receive a response message (an initialUE message) at step 730. Also, in case the initial UE message needsrevision, the HeNB GW may transmit the redirection message to the HeNBand then receive the response message.

However, if the redirection message has the entire information containedin the attach request message, the HeNB GW may perform step 740 withoutperforming steps 720 and 730.

At step 740, the HeNB GW may select the DCN and dedicated MME. The HeNBGW may select the dedicated MME by using information contained in theredirection message. Details are similar to those discussed above, sothe repetition is omitted herein.

The HeNB GW that selects the dedicated MME may transmit the initial UEmessage having the redirection message to the dedicated MME at step 750.Using the above-discussed process, the HeNB GW may enable the UE to beoffered service through a DCN.

FIG. 8 is a block diagram illustrating a configuration of the first MMEaccording to the first embodiment of the present invention.

Referring to FIG. 8, the first MME may be formed of a communication unit810, a control unit 820, and a storage unit 830.

The communication unit 810 may perform communication with other networkentities such as the eNB, the second MME, or the like.

The control unit 820 may control the reception of an initial UE messagefrom the eNB. The initial UE message may contain an NAS messagetransmitted from the UE.

Additionally, the control unit 820 may control the transmission andreception of an identification request message and an identificationresponse message to and from the second MME, and may check UE usage typeinformation contained in the received identification response message.Also, the control unit 820 may control the reception of an updatelocation ACK message from the HSS, and may check UE usage typeinformation contained in the update location ACK message. The controlunit 820 may determine whether to support a DCN according to the UEusage type information.

In case of failing to support the DCN as the result of determination,the control unit 820 may create a redirection message for rerouting theNAS message so as to allow the UE to be serviced from a dedicated MME,and then may transmit the redirection message to the eNB. Theredirection message may include all or part of information contained inthe NAS message. Additionally or alternatively, the redirection messagemay include all or part of information contained in the initial UEmessage.

Namely, the control unit 820 may deliver the received NAS message, as itis, to the eNB so that the eNB can forward the NAS message to thededicated MME. Therefore, the UE can be offered a service from the DCN.

Additionally, the control unit 820 may insert, in the redirectionmessage, at least one of MME UE S1AP ID, eNB UE S1AP ID, (revised)NAS-PDU (Protocol Data Unit), GUTI, GUMMEI (Globally Unique MMEIdentity), MMEGI (MME Group Identifier) or Null NRI (Network ResourceIdentifier)/SGSN group ID, GUMMEI type, S-TMSI (SAE Temporary MobileSubscriber Identity), TAI (Tracking Area Identity) and RRC establishmentcause, additional GUTI/P-TMSI, and information delivered to the MME/SGSNby the eNB. Therefore, using such information, the eNB may determine thededicated MME.

Further, the control unit 820 may control the reception of anidentification request message from the dedicated MME. After thisreception, the control unit 820 may check or verify the NAS messagecontained in the identification request message.

Further, the control unit 820 may identify the UE by using at least oneof GUTI, MME UE S1AP ID, and S-TMSI which are contained in the receivedidentification request message. Therefore, using an identificationresponse message, the control unit 820 may transmit MM contextcorresponding to the identified UE to the dedicated MME.

The storage unit 830 may store information contained in the initial UEmessage received from the eNB. Also, the storage unit 830 may storeinformation contained in the identification response message receivedfrom the second MME and information contained in the update location ACKmessage received from the HSS. Therefore, information stored in thestorage unit 830 may be used when the control unit 820 checks whetherthe DCN corresponding to the UE usage type information can be supported.Also, such information may be used when the control unit 820 creates thedirection message.

FIG. 9 is a block diagram illustrating a configuration of eNodeBaccording to the first embodiment of the present invention.

Referring to FIG. 9, the eNB may be formed of a communication unit 910,a control unit 920, and a storage unit 930.

The communication unit 910 may perform communication with other networkentities such as the first MME, the UE, the dedicated MME, or the like.

The control unit 920 may control the reception of an NAS messagecontained in an RRC message from the UE. The control unit 920 may createthe first initial UE message including the received NAS message and thentransmit it to the first MME. Information contained in the first initialUE message is discussed earlier in FIG. 3B, so the repetition is omittedherein.

In case the first MME that receives the first initial UE message fromthe eNB is not a dedicated MME, the control unit 920 may receive adirection message from the first MME. The redirection message mayinclude all or part of information contained in the NAS message.Additionally or alternatively, the redirection message may include allor part of information contained in the first initial UE message.

When the redirection message having the NAS message or the first initialUE message is received, the control unit 920 may forward the receivedmessage to the dedicated MME. Alternatively, the control unit 920 maycreate the second initial UE message having the NAS message contained inthe redirection message and then transmit it to the dedicated MME.

Therefore, the control unit 920 should determine the dedicated MME. Amethod for determining the dedicated MME is as follows.

The redirection message may contain at least one of MME UE S1AP ID, eNBUE S1AP ID, (revised) NAS-PDU (Protocol Data Unit), GUTI, GUMMEI(Globally Unique MME Identity), MMEGI (MME Group Identifier) or Null NRI(Network Resource Identifier)/SGSN group ID, GUMMEI type, S-TMSI (SAETemporary Mobile Subscriber Identity), TAI (Tracking Area Identity) andRRC establishment cause, additional GUTI/P-TMSI, and informationdelivered to the MME/SGSN by the eNB.

The first MME may set, as a value associated with the dedicated MME/SGSN154, at least one of GUMMEI, MMEGI or Null-NRI/SGSN Group ID, GUMMEIType, and S-TMSI and transmit it to the eNB. Then the control unit 920may select the dedicated MME by using information which is set as thevalue associated with the dedicated MME.

MMEGI or Null-NRI/SGSN Group ID may be used to identify a DCN in a PLMN.

GUMMEI may directly indicate the dedicated MME. Specifically, GUMMEI maybe formed of a PLMN identifier, MMEGI, and MMEC. In this case, a PLMNidentifier may be set as a serving PLMN of the UE 100 (namely, identicalto a PLMN part of TAI at step 102), MMEGI may be set as a valuecorresponding to a dedicated MME group, and MMEC (MME Code) may be setas a value corresponding to MMEC of the first MME. Therefore, thecontrol unit 920 may select a dedicated MME group by using a PLMNidentifier and MMEGI, and then select a dedicated MME by referring toMMEC.

Additionally, the control unit 920 may select MME/SGSN in the DCNindicated by MMEGI or Null-NRI/SGSN Group ID. If additional GUTI/P-TMSIidentifies MME/SGSN in the DCN indicated by MMEGI or Null-NRI/SGSN GroupID, MME/SGSN identified by additional GUTI/P-TMSI may be selected.

Meanwhile, in a network shared by several PLMNs, the control unit 920may select a DCN by using the following method.

The control unit 920 may select a dedicated MME by using at least one ofPLMN, MMEGI or Null-NRI/SGSN Group ID, and additional GUTI/P-TMSI whichare selected by the UE. The control unit 920 may select MME/SGSN in theDCN indicated by MMEGI or Null-NRI/SGSN Group ID in PLMN selected by theUE. If additional GUTI/P-TMSI identifies MME/SGSN in the DCN indicatedby MMEGI or Null-NRI/SGSN Group ID, MME/SGSN identified by additionalGUTI/P-TMSI may be selected. Namely, in case additional GUTI/P-TMSI isreceived, the control unit 920 may select a core network by consideringPLMN, MMEGI or Null-NRI/SGSN Group ID, and most significant 8 bits ofMMEC or NRI in additional GUTI/P-TMSI which are selected by the UE. Inthis case, PLMN in additional GUTI/P-TSMI may be ignored.

In this case, the control unit 920 may control the storage unit 930 tostore PLMN selected by and received from the UE, and may use storedinformation. Alternatively or additionally, the control unit 920 mayidentify PLMN selected by the UE through PLMN contained in theredirection message.

If it is not possible to find selectable MME in a DCN, the eNB mayselect MME in the default DCN or select again the MME.

Using the above-discussed process, the control unit 920 may enable theUE to be offered service through a DCN.

The storage unit 930 may store information contained in the RRC messagereceived from the eNB. Also, the storage unit 930 may store informationcontained in the identification response message received from the firstMME. Such information stored in the storage unit 930 may be used forcreating the first initial UE message or the second initial UE message.

FIG. 10 is a block diagram illustrating a configuration of UE accordingto the first embodiment of the present invention.

Referring to FIG. 10, the UE may be formed of a communication unit 1010,a control unit 1020, and a storage unit 1030.

The communication unit 1010 may perform communication with other networkentities such as the eNB, the first MME, or the like.

The control unit 1020 may create an RRC message having an NAS messageand transmit the created RRC message to the eNB through the RRC layer.The NAS message may include at least one of an attach request message, aTAU message, and an RAU message.

The NAS message may be contained in the first initial UE messagetransmitted to the first MME by the eNB. Also, the NAS message may becontained in the redirection message transmitted by the first MME. TheeNB that receives the redirection message having the NAS message maycreate the second initial UE message having the NAS message and thentransmit it to the dedicated MME.

The storage unit 1030 may store the created NAS message. Also, thestorage unit 1030 may store ID information for response to an IDrequest. Also, the storage unit 1030 may store authenticationinformation.

Second Embodiment

Hereinafter, a congestion control method and apparatus for anapplication according to the second embodiment of the present inventionwill be described.

According as the number of transmission packets is increased in anetwork, the performance of the network is degraded. A phenomenon ofrapid degradation in network performance is referred to as congestion.

Typically, when congestion occurs, ACM, SSAC, EAB, SCM, etc. are used asaccess control technique for UE. However, the UE fails to support anapplication-specific congestion control for data communication (ACDC).

If there is pending uplink data in the UE when the UE sends a trackingarea update (TAU) request message, the UE sets an active flag of the TAUrequest message to 1 and performs transmission. As a result, a userplane connection is established between the UE and the network.

Therefore, ACDC may be applied even when an active flag of the TAUrequest message is 1. The present invention proposes a method forapplying ACDC in case of TAU.

Additionally, in case the UE uses a power saving mode (PSM), the UEinserts an active timer in the TAU request message and transmits it tothe network. In this case as well, since the active flag may be set to 1when there is pending uplink data, ACDC should be applied. Also, the UEthat has the active timer and intends to enter PSM may be allowed tosend a service request regardless of ACDC with regard to the servicerequest sent during the period of time.

In this disclosure, ACDC may be determined according to operator'spolicy or regional regulations, providing a service in a disaster stateand also controlling congestion for a commercial service. Additionally,ACDC may be used as a similar concept with other functions capable of acongestion control for each application. An embodiment of the presentinvention may be similarly used generally in wireless communication suchas WLAN, Bluetooth, Zigbee, and the like in addition to thecommunication system discussed herein. Additionally, a mobilecommunication operator may provide UE with information for ACDC. Thismay be implemented using OMA standard called Management Object (MO) andthus referred to as ACDC MO. In order to deliver ACDC MO, a networkoperator may use other method such as presetting in the UE or SIM ratherthan using OMA standard.

FIG. 11 is a flow diagram illustrating a process in which UE appliesACDC in a TAU procedure according to the second embodiment of thepresent invention.

Referring to FIG. 11, the UE may decide to initiate the TAU procedure atstep 1110 according as a tracking area is changed. When initiating TAU,the UE may have uplink data to be transmitted through a network.

At step 1120, the UE may determine whether to set the active flag of theTAU message to 1 by determining whether there is uplink data in the UE.If there is no uplink data in the UE, the UE may not set the active flagto 1 and perform a normal TAU procedure at step 1130. Namely, the UE maytransmit a TAU message contained in an RRC message to the eNB withoutchecking application information.

If there is uplink data in the UE, the UE may set the active flag of theTAU message to 1. Then, at step 1140, the UE may determine informationabout an application that generates the uplink data.

In this case, the application information may be a criterion ofdetermination for applying ACDC, depending on an application from whichpending uplink data in the UE is generated. The application informationmay include an application category.

For example, if an application that generates uplink data belongs to anapplication category having lower priority, access may be disallowed(hereinafter, the term barring may be also used) as the result ofapplying ACDC and thus data may be not transmitted.

If an application that generate uplink data belongs to an applicationcategory having higher priority, a UE access process may be performedagain even in case of barring access by an application contained in anapplication category having lower priority.

Therefore, the UE may identify an application generatingtransmission-ready uplink data and check an application category byusing an identifier of the application and setting information thereof.Herein, this setting information may be contained in ACDC MO. Namely,the UE may map the application to an application category received withACDC MO. Through this procedure, the UE finds application information.

In this case, an application category contained in applicationinformation may be formed of bit information. For example, in caseinformation is formed of 3 bits, category #1 may be represented as 001and category #4 may be represented as 011. A value from 2 bits to 8 bitsmay be used.

The UE that finds application information may determine, at step 1150,whether to control access. Namely, the UE may determine whether toperform access barring.

Specifically, the UE may extracts, from system information block (SIB)information received from the eNB, a barring factor corresponding to anapplication category contained in application information. The UE maydetermine, based on a value specified or created through random numbergeneration using the barring factor, whether to perform access barringor not (i.e., pass).

At this time, access barring of UE may mean, for example, that the TAUprocedure of UE is not initiated. Namely, it may mean that the UE doesnot transmit the TAU message to the eNB.

However, as discussed above, even in case of access barring due to lowerpriority of a specific application category, the access procedure may beperformed if the UE supports ACDC in case radio resources of a userplane is requested for an application category having higher priority.

If the access of UE is passed, the UE may transmit the RRC messagecontaining the TAU message to the eNB at step 1260.

FIG. 12 is a flow diagram illustrating a process of applying ACDC in aTAU procedure according to the second embodiment of the presentinvention.

Referring to FIG. 12, the first upper layer unit of the UE may receive adata transmission request from the third upper layer unit at step 1210.Then the first upper layer unit may decide to initiate a TAU procedureat step 1220. Although an example in which the first upper layer unitinitiates the TAU procedure after receiving the data transmissionrequest is shown, the first upper layer unit may decide to initiate theTAU procedure and then receive the data transmission request from thethird upper layer unit.

Herein, the first upper layer unit may mean an apparatus for controllingoperations on an NAS layer. Also, the third upper layer unit may mean anapparatus for controlling operations on an application layer.

Meanwhile, when the UE initiates the TAU procedure, the UE may haveuplink data to be transmitted through a network.

If the UE supports ACDC, if user plane radio resource allocationaccording to uplink data is requested, and if it is possible to applyACDC to this request, the UE may set the active flag of the TAU messageto 1 at step 1230. Additionally, at step 1240, the UE may determineinformation about an application that generates the uplink data. Thisapplication information may contain an application category, which isdiscussed for example hereinafter. However, the application informationis not limited to application category information.

In this case, an application from which uplink data pending in the UE isgenerated may be a criterion for applying ACDC. For example, if anapplication that generates uplink data belongs to an applicationcategory having lower priority, access barring is determined as theresult of applying ACDC and thus data may be not transmitted.

Therefore, the UE may find an application category by identifying anapplication generating transmission-ready uplink data and by using anidentifier of the application and setting information thereof. Herein,this setting information may include category determination informationfor finding the category of an application, and may be contained in ACDCMO. Namely, the UE may map the application to an application categoryreceived with ACDC MO. This ACDC MO may be received through theapplication that generates transmission-ready uplink data. Through thisprocedure, the UE finds application information.

The UE that finds application information may transmit the applicationinformation to the second upper layer unit of the UE at step 1250.Herein, the second upper layer unit may mean an apparatus forcontrolling operations on a radio resource control (RRC) layer of theUE.

At this time, the first upper layer unit of the UE may form a call type,based on application category information for applying ACDC, the TAUmessage, and RRC establishment cause, and then may deliver thisinformation to the second upper layer unit.

In this case, application category information for applying ACDC may beformed of bit information for indicating an application category. Forexample, in case information is formed of 3 bits, category #1 may berepresented as 001 and category #4 may be represented as 011. A valuefrom 2 bits to 8 bits may be used.

At step 1260, the second upper layer unit that receives the TAU message,the application category information for applying ACDC, and the RRCestablishment cause from the first upper layer unit may determine UEaccess or not. In order to determine transmission of uplink data, the UEmay compare the application category information for applying ACDC withACDC information of SIB information received from the eNB.

Specifically, the UE may extracts, from SIB information, a barringfactor corresponding to the application category information receivedfrom the first upper layer unit. Then, based on the barring factor, theUE performs an access control, i.e., UE access barring or passing,depending on a value specified or created through random numbergeneration.

At this time, barring UE access may mean, for example, that the TAUprocedure of UE is not initiated. Namely, it may mean that the UE doesnot transmit the TAU message to the eNB.

However, even in case of access barring due to lower priority of aspecific application category, the access procedure may be performed ifthe UE supports ACDC when radio resources of a user plane is requestedfor an application category having higher priority.

If the access of UE is passed, the UE may transmit the RRC message tothe eNB at step 1270. This RRC message contains the TAU message receivedfrom the first upper layer unit of the UE.

Meanwhile, if the UE does not set the active flag to 1 at step 1230, theUE does not perform application category mapping for ACDC. Instead, theUE sets a call type complying with TAU initiation conditions, based onthe TAU message and the establishment cause, and then deliver thisinformation to the second upper layer unit. Thereafter, the second upperlayer unit transmits the TAU message contained in the RRC message to theeNB.

FIG. 13 is a flow diagram illustrating another process in which UEapplies ACDC in a TAU procedure according to the second embodiment ofthe present invention.

Referring to FIG. 13, the UE may decide to initiate the TAU procedure atstep 1310 according as a tracking area is changed. When initiating theTAU procedure, the UE may have uplink data to be transmitted through anetwork.

If there is uplink data in the UE, the UE may set the active flag of theTAU message to 1 at step 1320.

In this case, an application from which uplink data pending in the UE isgenerated may be a criterion for applying ACDC. For example, if anapplication that generates uplink data belongs to an applicationcategory having lower priority, access barring is determined as theresult of applying ACDC and thus data may be not transmitted.

If an application that generate uplink data belongs to an applicationcategory having higher priority, a UE access process may be performedagain even in case of barring access by an application contained in anapplication category having lower priority.

If the UE desires to use a power saving mode (PSM), the UE may set anactive timer value of the TAU message and, based on this, determinewhether to apply ACDC.

The term PSM may refer to a mode in which the UE sends data for a shorttime and then enters an idle state. Therefore, the UE that enters PSMmay contribute to reduction in network congestion.

Therefore, in case the UE sets the active flag of the TAU message to 1at step 1320, the UE may determine whether to set the active timer valueof the TAU message for using PSM at step 1330.

If the active timer value is set, the UE may skip a congestion controlthrough ACDC at step 1340. Therefore, at step 1350, the UE may transmitthe TAU request message to the network according to a normal TAUprocedure.

Namely, in case both the active flag and the active timer value are set,the UE may determine a call type corresponding to RRC establishmentcause corresponding to the TAU message, form the RRC message includingthis information, and transmit the RRC message to the eNB.

In another example, if the TAU procedure is completed in a state whereboth the active flag and the active timer value are set (i.e., in caseof transmitting the TAU request message to the eNB and then receivingthe TAU accept message from the eNB), the UE may skip ACDC for otherservice request message until entering a PSM state after the expirationof an active timer.

Meanwhile, if the UE fails to set the active timer value of TAU at step1330, the UE may apply ACDC to uplink data. Namely, the UE may findapplication information (e.g., application category) associated with thegeneration of uplink data at step 1370 and then determine access or notof UE according to the application information at step 1380. Details arediscussed above in FIG. 11, so the repetition is omitted herein.

Meanwhile, if the UE does not set the active flag to 1 at step 1320, theUE may perform a normal TAU procedure at step 1390.

Namely, the UE may select a call type for the TAU message and RRCestablishment cause without application category mapping, form the RRCmessage having such information, and transmit the RRC message to theeNB.

FIG. 14 is a flow diagram illustrating another process of applying ACDCin a TAU procedure according to the second embodiment of the presentinvention.

While FIG. 12 shows a case in which an active timer is not set, FIG. 14shows a case in which the active timer is set.

Referring to FIG. 14, the first upper layer unit of the UE may receive adata transmission request from the third upper layer unit at step 1410.Then the first upper layer unit may decide to initiate a TAU procedureat step 1420. Alternatively, the first upper layer unit may decide toinitiate the TAU procedure and then receive the data transmissionrequest from the third upper layer unit.

Herein, the first upper layer unit may mean an apparatus for controllingoperations on an NAS layer. Also, the third upper layer unit may mean anapparatus for controlling operations on an application layer.

When the UE initiates the TAU procedure, the UE may have uplink data tobe transmitted through a network.

If the UE supports ACDC, if user plane radio resource allocationaccording to uplink data is requested, and if it is possible to applyACDC to this request, the UE may set the active flag of the TAU messageto 1 at step 1430. Additionally, at step 1440, the UE may set the activetimer of the TAU message.

The case where the UE sets the active timer of the TAU message may meana case in which the UE uses PSM. The term PSM may refer to a mode inwhich the UE sends data for a short time and then enters an idle state.Therefore, the UE that enters PSM may contribute to reduction in networkcongestion.

Therefore, if the UE sets the active flag to 1 because of the presenceof uplink data to be transmitted, and if the UE sets the active timervalue for the use of PSM, the UE may not require a congestion controlthrough ACDC.

Therefore, at step 1450, the first upper layer unit may determine a calltype corresponding to RRC establishment cause corresponding to the TAUmessage, and transmit this information to the second upper layer unit.At this time, the second upper layer unit may mean, but not limited to,an apparatus for controlling operations on the RRC layer.

Thereafter, the second upper layer unit may form the RRC message havingthe above information at step 1460, and transmit the RRC message to theeNB at step 1470.

Meanwhile, if the TAU procedure is completed in a state where both theactive flag and the active timer value are set (i.e., in case oftransmitting the TAU request message to the eNB and then receiving theTAU accept message from the eNB), the UE may skip ACDC for other servicerequest message until entering a PSM state after the expiration of anactive timer. If the first upper layer unit of the UE does not set theactive flag to 1, the first upper layer unit may determine a call typecorresponding to the TAU message and RRC establishment cause withoutapplication category mapping for using ACDC according to a normal TAUprocedure, and transmit this to the second upper layer unit. Then thesecond upper layer unit may form the RRC message having the aboveinformation and transmit the RRC message to the eNB.

FIG. 15 is a block diagram illustrating a configuration of UE accordingto the second embodiment of the present invention.

Referring to FIG. 15, the UE according to the second embodiment includesa transceiver unit 1505, a control unit 1510, a multiplexing anddemultiplexing unit 1520, a control message processing unit 1545, andvarious upper layer processing units 1525, 1530 and 1535. Although threeupper layer processing units 1525, 1530 and 1535 are shown, this isexemplary only and not to be considered as a limitation of thisinvention.

The transceiver unit 1505 may perform communication with other networkentities. The transceiver unit 1505 may receive data and control signalsthrough a downlink channel of a serving cell and also transmit data andcontrol signals through an uplink channel.

The multiplexing and demultiplexing unit 1520 may multiplex datagenerated at the upper layer processing units 1525, 1530 and 1535 or thecontrol message processing unit 1545. Also, the multiplexing anddemultiplexing unit 1520 may demultiplex data received from thetransceiver unit 1505 and then deliver it to the upper layer processingunits 1525, 1530 and 1535 or the control message processing unit 1545.

The control message processing unit 1545 is a kind of RRC layerapparatus and may process a control message received from the eNB.

The upper layer processing units 1525, 1530 and 1535 may be formed ofthe first upper layer processing unit 1525, the second upper layerprocessing unit 1530, and the third upper layer processing unit 1535.The UE may further include a plurality of upper layer processing units.

The first upper layer processing unit 1525 may control operations on theNAS layer, and the second upper layer processing unit 1530 may controloperations on the RRC layer. Also, the third upper layer processing unit1535 may control operations on the application layer. Such upper layerprocessing units may be formed for each service. The upper layerprocessing units may process data created in a user service such as FTP(File Transfer Protocol) or VoIP (Voice over Internet Protocol) and thendeliver it to the multiplexing and demultiplexing unit 1520, or mayprocess data delivered from the multiplexing and demultiplexing unit1520 and then deliver it to a service application on the upper layer.

The control unit 1510 may check scheduling commands, e.g., reversegrants, received through the transceiver unit 1505 and then control thetransceiver unit 1505 and the multiplexing and demultiplexing unit 1520so that reverse transmission can be performed with suitable transmissionresources at a suitable time point. Also, the control unit 1510 controlsall procedures applying ACDC in the TAU procedure. Namely, the controlunit 1510 performs control operations associated with the operation ofUE as shown in FIGS. 11 to 14.

Specifically, the control unit 1510 may control the first upper layerprocessing unit to determine whether to initiate the TAU procedure. Atthis time, if uplink data transmission is requested through the thirdupper layer processing unit, the control unit 1510 may control the firstupper layer processing unit to determine whether to initiate the TAUprocedure. Alternatively or additionally, the control unit 1510 maycontrol the reception of a data transmission request from the thirdupper layer processing unit after the first upper layer processing unitdetermines the initiation of the TAU procedure. Also, the control unit1510 may control a value of the active flag to be set to 1, depending onwhether there is transmission-ready uplink data. If the value of theactive flag is not set to 1, the control unit 1510 may controlperforming a normal TAU procedure. If the value of the active flag isset to 1, the control unit 1510 may control determining applicationinformation of an application from which transmission-ready uplink datais generated. This application information may include an applicationcategory. Additionally, the control unit 1510 may control delivering theapplication information from the first upper layer processing unit tothe second upper layer processing unit. Also, the control unit 1510 maydetermine whether to allow the access of UE, using the applicationinformation through the second upper layer processing unit. The controlunit 1510 may extract a barring factor corresponding to an applicationcategory from SIB information received from the eNB. The control unit1510 may determine UE access barring or passing, depending on a valuespecified or created through random number generation using the barringfactor.

However, even in case of access barring due to lower priority of aspecific application category, the control unit 1510 may perform theaccess procedure if the UE supports ACDC when radio resources of a userplane is requested for an application category having higher priority.

If the access of UE is passed, the control unit 1510 may controltransmitting the RRC message having the TAU message to the eNB throughthe second upper layer processing unit.

Meanwhile, with regard to UE that uses PSM, the control unit 1510 maycontrol determining whether to apply ACDC. The term PSM may refer to amode in which the UE sends data for a short time and then enters an idlestate. Therefore, the UE that enters PSM may contribute to reduction innetwork congestion.

Therefore, in case of setting the active flag to 1 (i.e.,transmission-ready uplink data exists) and in case of setting the activetimer value so as to operate in PSM, the control unit 1510 may controlperforming no congestion control through ACDC. Therefore, the controlunit 1510 may control performing a normal TAU procedure. Specifically,the control unit 1510 may control the first upper layer processing unitto determine a call type corresponding to RRC establishment causecorresponding to the TAU message, and transmit this information to thesecond upper layer processing unit. Further, the control unit 1510 maycontrol the second upper layer processing unit to form the RRC messagehaving the above information and transmit the RRC message to the eNB.

Meanwhile, if the TAU procedure is completed in a state where both theactive flag and the active timer value are set (i.e., in case oftransmitting the TAU request message to the eNB and then receiving theTAU accept message from the eNB), the control unit 1510 may skip ACDCfor other service request message until entering a PSM state after theexpiration of an active timer.

Third Embodiment

Hereinafter, a method and apparatus for providing a multimedia broadcastmulticast service (MBMS) according to the third embodiment of thepresent invention will be described.

In case of providing data to UE through MBMS, a group communicationservice application server (GCS AS) and/or a broadcast/multicast servicecenter (BM-SC) may transmit information associated with MBMS servicearea, and the UE may receive MBMS data based on the MBMS service area.However, since the MBMS service area covers a wide range, MME may changethe MBMS service area even when considerable traffic is generated due tonumerous users in a specific area. Therefore, in case there are manyusers in a specific area, the MME may transmit a message for instructinga setup or modification of MBMS session to a multi cell/multicastcoordination entity (MCE) contained in the MBMS service area so that theMBMS session can be created or changed and finally MBMS data can betransmitted to the UE. However, this method for creating or changing theMBMS session may invite necessary signaling. Therefore, this inventionproposes a method for transmitting and receiving data in a smaller MBMSarea than the MBMS service area.

FIGS. 16A and 16B are flow diagrams illustrating a method for providingan MBMS service according to the third embodiment of the presentinvention.

In this embodiment, an MBMS applicable area may be a smaller area thanthe MBMS service area.

Referring to FIG. 16A, the GCS AS may transmit an activate MBMS bearerrequest message to the BM-SC at step 1601. Alternatively, the GCS AS maytransmit a modify MBMS bearer request message for modifying an activatedMBMS bearer to the BM-SC at step 1604. The activate MBMS bearer requestmessage and the modify MBMS bearer request message may containinformation about an MBMS broadcast area. The GCS AS may determine theMBMS broadcast area information, based on information (e.g., a UElocation which may be represented as a cell identifier, an MBSFN areaidentifier, an MBMS service area, etc.) obtained from the UE throughapplication signaling and/or setting information. The MBMS broadcastarea information may include an MBMS service area, an MBSFN areaidentifier list, and/or a cell list (i.e., an ECGI (E-UTRAN cell globalidentifier) list).

At step 1602, the BM-SC that receives the activate MBMS bearer requestmessage may allocate resources in an MBMS system so as to support a dataflow. Alternatively, at step 1605, the BM-SC that receives the modifyMBMS bearer request message may determine whether to modify the MBMSbearer.

If a cell list is contained in the MBMS broadcast area informationreceived by the BM-SC, the BM-SC may induce the MBMS service area fromthe cell list information. For this, the BM-SC may have mappinginformation between the cell list information and the MBMS service area.In this case, if the MBMS service area is received from the GCS AS, theBM-SC may overwrite the received MBMS service area with the induced MBMSservice area. Thereafter, the BM-SC may insert mapped MBMS service areaand/or cell list in a message sent to MBMS GW for requesting MBMS beareractivation and/or MBMS bearer modification. Of course, even though acell list is contained in the MBMS broadcast area information receivedby the BM-SC, the MBMS service area information received from the GCS ASmay be used as it is. In case the GCS AS sends the cell list and theMBMS service area, whether the BM-SC will use them as received or use anew MBMS service area induced from the cell list may depend on anoperator's policy and/or setting.

If the BM-SC induces the MBMS service area from the cell list, the BM-SCmay deliver, to the GCS AS, the induced MBMS service area (i.e., theMBMS service area contained in a message sent to the MBMS GW forrequesting MBMS bearer activation and/or MBMS bearer modification)through a response message for the request of MBMS bearer activationand/or MBMS bearer modification at step 1603 or 1606. If the BM-SC doesnot induce the MBMS service area from the cell list, or if the receivedMBMS broadcast area information does not contain the cell list, theBM-SC may not insert the MBMS service area in the response message forthe request of MBMS bearer activation and/or MBMS bearer modification.

The GCS AS may transmit, to the UE, the MBMS service area received atstep 1603 or 1606. If the GCS AS fails to receive the MBMS service areaat step 1603 or 1606, the GCS AS may transmit, to the UE, the MBMSservice area transmitted to the BM-SC at step 1601 or 1604. Although anycell is located in the MBMS service area, MBMS may not be applied if theMBMS bearer is activated using the cell list. Therefore, in case theMBMS service area received from the GCS AS is not contained in the MBMSservice area information broadcasted by the cell, the UE can know thatMBMS is not applied to a service in that cell. However, in case the MBMSservice area received from the GCS AS is contained in the MBMS servicearea information broadcasted by the cell, the UE may not know whetherMBMS is applied or not to a service in that cell.

Referring to FIG. 16B, the MME may receive, from MBMS-GW, a message thatcontains the MBMS service area and the cell list (i.e., the ECGI list).Also, a message transmitted to the MCE by the MME may contain parametersreceived through the BM-SC by the MBMS-GW. In this case, theseparameters may include a temporary mobile group identity (TMGI), FlowID,QoS, MBMS broadcast area information, a start time, and the like. TheMBMS broadcasts area information may include the MBMS service area orthe cell list information. If the cell list information is contained inthe MBMS broadcast area information, this information may be mapped tothe MBMS service area by the BM-SC. The BM-SC may deliver, to the GCSAS, information (MBMS service area) created from the cell listinformation.

The MME that receives the message including the MBMS service area andthe cell list from the MBMS GW may transmit a message (hereinafter,referred to as an MBMS session setup or modify message) for a setup ormodification of MBMS session to the MCE. At this time, the MME may sendthe MBMS session setup or modify message to only the MCE that controlsthe received cell list.

For this, at step 1610 for M3 setup with the MME, the MCE may deliver,to the MME, an M3 setup request message having a cell identifier listand/or an identifier list of the eNB connected to the MCE.

The M3 setup request message may be defined as shown in Table 2 andTable 3.

TABLE 2 IE/Group IE type and Semantics Assigned Name Presence Rangereference description Criticality Criticality Message Type M 9.2.1.1 YESreject Global MCE ID M 9.2.1.10 YES reject MCE Name O PrintableStringYES ignore (1 . . . 150, . . . ) MBMS Service 1 YES reject AreaList >MBMS 1 to Supported GLOBAL reject Service Area <maxnoof- MBMS ListItem MBMSService- Service Area AreaIdentities- Identities in PerMCE> theMCE >>MBMS M OCTET MBMS Service Area 1 STRING(2) Service Area Identitiesas defined in TS 23.003 [13]. eNB list or cell 1 to n list > Global eNBID or ECGI

TABLE 3 Range bound Explanation maxnoofMBMSServiceArea- Maximum no. ofService Area IdentitiesPerMCE Identities per MCE. The value formaxnoofMBMSServiceArea- Identities is 65536.

At step 1620, the MME that receives the above-message may transmit an M3setup response message for the setup request message.

At this time, the MME may identify the eNB by using a global eNB ID partof the cell list information (ECGI) and also check serving MCEinformation for each eNB contained in the setup request message.Therefore, the MME can determine the MCE to which the MBMS session setupor modify message will be transmitted. In this manner, the MME may sendthe MBMS session setup or modify message to a few of MCEs, thuseffecting a reduction in signaling.

Meanwhile, the MME may receive, from the eNB, an S1 setup requestmessage or eNB configuration update request message which contains anidentifier of MCE connected to the eNB or a cell in the eNB. Therefore,in similar manner using similar information as discussed above, the MMEmay determine the MCE to which the MBMS configuration message will betransmitted.

FIG. 17 is another flow diagram illustrating a method for providing anMBMS service according to the third embodiment of the present invention.

Referring to FIG. 17, the MME may receive, from MBMS-GW, a message thatcontains the MBMS service area and the cell list (i.e., the ECGI list).Details are discussed earlier in FIG. 16B, so the repetition is omittedherein.

The MME that receives the message including the MBMS service area andthe cell list from the MBMS GW may transmit the MBMS session setup ormodify message to the MCE. At this time, the MME may send the MBMSsession setup or modify message to only the MCE that controls thereceived cell list.

For this, at step 1710, the MCE may deliver, to the MME, an MCEconfiguration update message having a cell identifier list and/or anidentifier list of the eNB connected to the MCE.

The MCE configuration update message may be defined as shown in Table 4and Table 5.

TABLE 4 IE type and Semantics Assigned IE/Group Name Presence Rangereference description Criticality Criticality Message Type M 9.2.1.1 YESreject Global MCE ID O 9.2.1.10 YES reject MCE Name O PrintableStringYES ignore (1 . . . 150, . . . ) MBMS Service 0 . . . 1 YES reject AreaList >MBMS Service 1 to Supported GLOBAL reject Area List Item <maxnoof-MBMS MBMSService- Service AreaIdentities- Area PerMCE> Identities in theMCE >>MBMS Service M OCTET MBMS Area 1 STRING(2) Service Area Identitiesas defined in TS 23.003 [13]. eNB list or cell 1 to n list > Global eNBID or ECGI

TABLE 5 Range bound Explanation maxnoofMBMSServiceArea- Maximum no. ofService Area IdentitiesPerMCE Identities per MCE. The value formaxnoofMBMSServiceArea- Identities is 65536.

At step 1720, the MME that receives the above-message may transmit anMCE configuration update acknowledge message.

At this time, the MME may identify the eNB by using a global eNB ID partof the cell list information (ECGI) and also check serving MCEinformation for each eNB contained in the MCE configuration updatemessage. In this manner, the MME may send the MBMS session setup ormodify message to a few of MCEs, thus effecting a reduction insignaling.

FIG. 18 is a block diagram illustrating a configuration of MME accordingto the third embodiment of the present invention.

Referring to FIG. 18, the MME may be formed of a communication unit1810, a control unit 1820, and a storage unit 1830.

The communication unit 1810 may perform communication with other networkentities such as the MBMS GW, the MCE, the eNB, or the like.

The control unit 1820 may control the reception of a message having theMBMS service area and the cell list from the MBMS GW. This message maycontain parameters received through the BM-SC by the MBMS-GW. In thiscase, these parameters may include TMGI, FlowID, QoS, MBMS broadcastarea information, a start time, and the like. Details are discussedearlier in FIG. 16, so the repetition is omitted herein.

The control unit 1820 may control the reception of an M3 setup requestmessage from the MCE at M3 setup with the MCE. The M3 setup requestmessage may have a cell identifier list and/or an identifier list of theeNB connected to the MCE. The control unit 1820 may control thetransmission of a setup response message for the setup request message.

Additionally, the control unit 1820 may identify the eNB by using aglobal eNB ID part of the cell list information (ECGI) and also checkserving MCE information for each eNB contained in the setup requestmessage. Therefore, the control unit 1820 can determine the MCE to whichthe MBMS session setup or modify message will be transmitted.

Meanwhile, a cell identifier list and/or an identifier list of the eNBmay be contained in the MCE configuration update message and transmittedto the MME from the MCE.

Additionally, the control unit 1820 may control the reception, from theeNB, of the S1 setup request message or eNB configuration update requestmessage having an identifier of MCE connected to the eNB or a cell inthe eNB. Using the above information, the control unit 1820 maydetermine the MCE to which the MBMS session setup or modify message willbe transmitted. This method is discussed above.

The storage unit 1830 may store information received from the MBMS GW.Also, the storage unit 1830 may store information received from the MCEor the eNB. Therefore, such information stored in the storage unit 1830may be used for determining the MCE to which the MBMS session setup ormodify message will be transmitted.

Further, the storage unit 1830 may store a list of MCE determined totransmit the MBMS session setup or modify message.

FIG. 19 is a block diagram illustrating a configuration of MCE accordingto the third embodiment of the present invention.

Referring to FIG. 19, the MCE may be formed of a communication unit1910, a control unit 1920, and a storage unit 1930.

The communication unit 1910 may perform communication with other networkentities such as the MME, the eNB, or the like.

The control unit 1920 may control the transmission of the M3 setuprequest message to the MME for M3 setup with the MME. The control unit1920 may insert, in the M3 setup request message, a cell identifier listand/or an identifier list of the eNB connected to the MCE. Also, thecontrol unit 1930 may control the reception of the setup responsemessage for the setup request message.

Additionally, the control unit 1920 may control the transmission, to theMME, of the M3 setup request message having a cell identifier listand/or an identifier list of the eNB connected to the MCE, and alsocontrol the reception of the MCE configuration update acknowledgemessage.

Further, the control unit 1920 may control the reception of the MBMSsession setup or modify message from the MME in case the MCE is selectedby the MME.

The storage unit 1930 may store a cell identifier list and/or anidentifier list of the eNB connected to the MCE. Therefore, suchinformation stored in the storage unit 1930 may be used for creating theM3 setup request message or the MCE configuration update message.

The present invention may be embodied in many different forms withoutchanging technical subject matters and essential features as will beunderstood by those skilled in the art. Therefore, embodiments set forthherein are exemplary only and not to be construed as a limitation.

In embodiments, all steps and messages are not a target for selectiveimplementation or omission. Additionally, in each embodiment, steps maynot be always performed in the order described and may be changed inorder. Similarly, delivery of messages may not be always performed inthe order described and may be changed in order. Each step and messagingmay be performed independently.

The whole or parts of exemplary contents in embodiments are provided topromote understanding by showing a detailed embodiment of thisinvention. Therefore, the detailed contents may be regarded asexpressing a part of method and apparatus proposed by this invention.Namely, with regard to such contents, a syntax-based approach may bemore desirable than a semantics-based approach.

While the present invention has been particularly shown and describedwith reference to an exemplary embodiment thereof, it will be understoodby those skilled in the art that various changes in form and details maybe made therein without departing from the spirit and scope of theinvention as defined by the appended claims.

What is claimed is:
 1. A method by a base station in a wirelesscommunication system, the method comprising: receiving a non-accessstratum (NAS) message from a user equipment (UE); transmitting a firstinitial UE message including the NAS message to a first mobilitymanagement entity (MME); receiving a reroute message including the firstinitial UE message from the first MME, if a reroute is determined by thefirst MME; and transmitting a second initial UE message including theNAS message to a second MME supporting a dedicated core network for theUE, wherein the second MME is selected based on a selected public landmobile network (PLMN).
 2. The method of claim 1, wherein transmittingthe second initial UE message comprises determining the second MMEsupporting the dedicated core network for the UE, based on informationcontained in the reroute message.
 3. The method of claim 2, whereindetermining the second MME includes determining the second MME, based onat least one of an MME group identifier (MMEGI), a null-network resourceidentifier (null-NRI)/serving GPRS support node (SGSN) group identifier,or an additional globally unique temporary UE identity(GUTI)/P-temporary mobile subscriber identity (P-TMSI), all of which arecontained in the reroute message.
 4. The method of claim 1, wherein theNAS message includes at least one of an attach request message, atracking area update message, or a routing area update message.
 5. Themethod of claim 1, wherein the selected PLMN is stored in the basestation.
 6. The method of claim 1, wherein the selected PLMN isidentified based on information included in the reroute message.
 7. Abase station in a wireless communication system, the base stationcomprising: a transceiver and a controller coupled with the transceiverand configured to control the transceiver to: receive a non-accessstratum (NAS) message from a user equipment (UE), transmit a firstinitial UE message including the NAS message to a first mobilitymanagement entity (MME), receive a reroute message including the firstinitial UE message from the first MME, if a reroute is determined by thefirst MME, and transmit a second initial UE message including the NASmessage to a second MME supporting a dedicated core network for the UE,wherein the second MME is selected based on a selected public landmobile network (PLMN).
 8. The base station of claim 7, wherein thecontroller is further configured to determine the second MME supportingthe dedicated core network for the UE, based on information contained inthe reroute message.
 9. The base station of claim 7, wherein thecontroller is further configured to determine the second MME, based onat least one of an MME group identifier (MMEGI), a null-network resourceidentifier (null-NRI)/serving GPRS support node (SGSN) group identifier,or an additional globally unique temporary UE identity(GUTI)/P-temporary mobile subscriber identity (P-TMSI), all of which arecontained in the reroute message.
 10. The base station of claim 7,wherein the NAS message includes at least one of an attach requestmessage, a tracking area update message, or a routing area updatemessage.
 11. The base station of claim 7, wherein the selected PLMN isstored in the base station.
 12. The base station of claim 7, wherein theselected PLMN is identified based on information included in the reroutemessage.
 13. A method by a first mobility management entity (MME) in awireless communication system, the method comprising: receiving a firstinitial user equipment (UE) message including a non-access stratum (NAS)message from a base station; and transmitting a reroute messageincluding the first initial UE message, if a reroute is determined bythe first MME, wherein if the reroute message is transmitted, a secondinitial UE message including the NAS message is transmitted to a secondMME supporting a dedicated core network for the UE, and wherein thesecond MME is selected based on a selected public land mobile network(PLMN).
 14. The method of claim 13, wherein the second MME isdetermined, based on at least one of an MME group identifier (MMEGI), anull-network resource identifier (null-NRI)/serving GPRS support node(SGSN) group identifier, or an additional globally unique temporary UEidentity (GUTI)/P-temporary mobile subscriber identity (P-TMSI), all ofwhich are contained in the reroute message.
 15. The method of claim 13,wherein the NAS message includes at least one of an attach requestmessage, a tracking area update message, or a routing area updatemessage.
 16. The method of claim 13, wherein the UE usage typeinformation is received from one of other MME and a home subscriberserver (HSS).
 17. The method of claim 13, wherein the selected PLMN isstored in the base station.
 18. The method of claim 13, wherein theselected PLMN is identified based on information included in the reroutemessage.
 19. A first mobility management entity (MME) in a wirelesscommunication system, the first MME comprising: a transceiver; and acontroller coupled with the transceiver and configured to control thetransceiver to: receive a first initial user equipment (UE) messageincluding a non-access stratum (NAS) message from a base station, andtransmit a reroute message including the first initial UE message, if areroute is determined by the first MME, wherein if the reroute messageis transmitted, a second initial UE message including the NAS message istransmitted to a second MME supporting a dedicated core network for theUE, and wherein the second MME is selected based on a selected publicland mobile network (PLMN).
 20. The first MME of claim 19, wherein thesecond MME is determined, based on at least one of an MME groupidentifier (MMEGI), a null-network resource identifier(null-NRI)/serving GPRS support node (SGSN) group identifier, or anadditional globally unique temporary UE identity (GUTI)/P-temporarymobile subscriber identity (P-TMSI), all of which are contained in thereroute message.
 21. The first MME of claim 19, wherein the NAS messageincludes at least one of an attach request message, a tracking areaupdate message, or a routing area update message.
 22. The first MME ofclaim 19, wherein the UE usage type information is received from one ofother MME and a home subscriber server (HSS).
 23. The first MME of claim19, wherein the selected PLMN is stored in the base station.
 24. Thefirst MME of claim 19, wherein the selected PLMN is identified based oninformation included in the reroute message.